Biochar-Driven Enhancements in Soil Fertility and Agricultural Sustainability
Abstract
Soil degradation driven by climate change, deforestation, and unsustainable agriculture threatens global ecological resilience and food security. Current estimates suggest that at least 24% of the world's agricultural land is degraded by overuse, and this proportion is expected to increase in the coming years. This review presents advances in biochar as a soil amendment, emphasising its structural, chemical, and biological impacts on soil fertility. Biochar possesses a highly porous structure with a specific surface area ranging from 10 to 800 m2 per gram, featuring resilient aromatic carbon frameworks and effective nutrient-holding capabilities. Empirical studies reveal that biochar amendments enhance soil porosity by 5–15%, reduce bulk density by 3–12%, and elevate microbial biomass by up to 380% in soils amended with Miscanthus straw biochar. Nutrient dynamics are markedly improved, with nitrogen adsorption capacities reaching 635 mg kg-1 and phosphorus release rates as high as 1664 mg kg-1, depending on feedstock and pyrolysis conditions. However, potential risks, including heavy metal retention (e.g., PAH concentrations up to 3574 μg kg-1 in amended soils) and pH alterations, necessitate judicious management. Collectively, this review positions biochar as a transformative tool for sustainable soil management, contingent upon context-specific application strategies and rigorous monitoring of long-term environmental impacts.